The same turbulent forces that heat the waters of Calistoga’s famous hot springs and geysers once turned a forest to stone. 3.5 million years ago an ancient volcano knocked down and buried a forest, including a grove of enormous redwoods. Their grey stone effigies were uncovered in 1857 and excavated over the following decades.
Petrified trees are not uncommon. Once buried in volcanic ash and deprived of oxygen, over a period ranging from a hundred to hundreds of thousands of years, the organic materials that make up organic matter, like trees, are replaced by silica. The resulting stone fossils retain all of the markings of the original trees, including bark, rings, and knots, and lie exactly as they fell millions of years ago. Petrified forests have been found all over the world, but the forest in Calistoga is remarkable for the sheer size of the enormous redwoods preserved, some thought to have been as old as 2000 years when they were felled. They are among the largest petrified trees found anywhere.
The property has changed hands many times over the decades since its discovery, but it is still a small family-run operation. In the 1880s Robert Louis Stevenson wrote about his visit to the forest and its eccentric owner in his book The Silverado Squatters, and there is now a tree named for him along the trail. The height of the forest’s notoriety and excavation work was started in 1914 under the guidance of Ollie Bockee, whose publicity efforts included sending a log off to the city of New York and getting another log included in the wonders on display at the San Francisco Pan-Pacific Exposition of 1915.
Today, about a half mile of trail wanders though the woodland with signs and markers indicating specific tress, some of which are only half excavated. A gift shop located in the ground floor of the home Ollie Bockee built has a collection of fossils and petrified wood from around the world on display and for sale.